The products: All of our actions — blinks, hand waves, stomach crunches — start with electrical signals from the brain. If you can't stand the thought of stomach crunches, you can always bypass your brain and strap on some electrodes. When electricity hits your abs, the idea goes, the muscles will tighten — as if you were working out.

Consumers interested in "electric exercise" have plenty of options. Many health spas offer electronic muscle stimulation (EMS) as a part of their "slimming" treatments, and Internet sites sell home use EMS devices.

For example, for about $150, you can slip into your own Slendertone Flex, a belt that delivers electricity to the abdominal muscles. It provides enough juice to cause intense contractions that would score an 8 or more on a 1 to 10 scale, says John Porcari, an exercise physiologist at the University of Wisconsin at La Crosse who published a company-funded clinical study of the device in 2005. "It feels like a muscle cramp."

Doctors and physical therapists use EMS to ease pain and strengthen muscles damaged by injury or stroke. Beyond this, the devices have a rocky history.

In the 1970s, the Food and Drug Administration sent "wanted" posters to post offices across the U.S. to warn about the Relaxacisor, a high-voltage vest that provided more shocks than results. In 2002, the FDA reported that unapproved EMS devices might burn users or interfere with pacemakers.

And in 2003, the Federal Trade Commission levied a $5-million fine against the marketers of the AbTronic, a heavily advertised belt that promised "rock-hard" abs without effort.

The claims: Infomercials, newspaper ads and Internet sites continue to promise incredible results, no workout required. The website for Body Beauté, a health spa with outlets in Beverly Hills and Newport Beach, claims its EMS treatment is "equivalent to 1,500 sit-ups per hour" and that EMS is an integral part of a weight-loss plan that can help one lose as much as 20 pounds in three weeks.

A website hawking the Vital Stim EMS 4000, a device featuring two electrified pads that can be placed practically anywhere on the body, boasts that the "revolutionary" product can "build the same rippling muscles that steroids promised."

Pitches for the Slendertone Flex are more reserved. A TV spot calls it "the clinically proven solution to get the tighter, more toned abs you've always wanted and that the Slendertone Flex is the "first ab belt ever to be cleared for sale by the FDA."

"Slender" is in the name, but the Slendertone Flex is not for weight loss, says Susan Henken, spokesperson for Slendertone USA. The belt can firm stomach muscles but "we'd never say that you'd get six-pack abs."

Bottom line: Exercise belts of the past routinely burned and shocked people without working muscles, but the Slendertone Flex really is FDA-approved for "toning, strengthening and firming abdominal muscles." Porcari's 2005 study in the Journal of Sports Science and Medicine, found that all 24 subjects who used the belt five days a week for eight weeks said their abs felt firmer and more toned. Stomach-crunch tests showed a strength gain — about 70% more than a control group. Lab measurements showed they lost more than an inch from their waistline, but they didn't shed body fat or drop pounds.

The device could be especially helpful for people who can't do regular sit-ups, including people with back trouble, Porcari says. "But anyone who expects to look like the people in the infomercials will be disappointed."

Claims of "1,500 sit-ups an hour" or "rippling muscles" from EMS are ludicrous, and no EMS device could dramatically flatten a stomach or speed weight loss, he says. A person needs to burn calories to lose weight, and it's not possible to burn significant calories through contractions alone. "You'd have to do thousands of actual sit-ups to lose any weight," adds Wayne Miller, an exercise physiologist at George Washington University. "Anyone who can do that many sit-ups probably doesn't need to."

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